JP2023058938A - Control device, control system, and time synchronization method - Google Patents

Abstract

To achieve time synchronization by arbitrating from information shared among a plurality of control devices.SOLUTION: A control device constituting part of a control system that performs control over a controlled device includes: a communication unit that transmits and receives information about the control device; a shared data storage unit that stores time synchronization information received from a control device, which is a time master device, via the communication unit; a synchronization update unit that controls storage of the time synchronization information in the shared data storage unit of its own control device in synchronization with storage in a shared data storage unit of another control device; a time management unit that detects an amount of deviation of a clock with respect to the time master device, and stores the detected amount of deviation of the clock in the shared data storage unit; and an arbitration unit that selects a time master device based on the amount of deviation of the clock stored in the shared data storage unit, and arbitrates with the other control device, and determines the time master device.SELECTED DRAWING: Figure 3

Description

The present invention relates to a control device that constitutes a control system.

Control systems are installed in various social infrastructure systems. In a control system, a social infrastructure system is automated and made efficient by automating and improving the efficiency of the control system by a plurality of control devices that execute arithmetic processing.

A control device that constitutes such a control system acquires acquired information such as various state quantities from detection devices such as sensors installed in the field, and the central processing unit of the control device executes arithmetic processing. The control device outputs a control command to operating devices such as motors and actuators installed in the field, and controls the operating devices to be controlled in real time.

Also, a control system in a large-scale social infrastructure system comprises a distributed control system in which a plurality of control devices are connected via a common network. A distributed control system aggregates acquired information acquired from a plurality of detection devices installed in a vast field into a single control device and executes arithmetic processing. Such a distributed control system divides the roles of a control device that executes arithmetic processing and a control device that outputs a control command, and executes control with high efficiency.

A shared memory method is available as a method for synchronizing data between controllers in a distributed control system. In the shared memory method, each control device that constitutes the distributed control system has a shared memory in the memory mounted in each control device, and the own control device transmits data stored in the shared memory to other control devices. Send. As a result, data is shared between the control devices, and the communication load between the control devices is reduced.

Furthermore, by synchronizing the time of multiple control devices and outputting control commands to the controlled object at the same timing, it is possible to execute multiple processes at the same time and process them in chronological order at the desired time. Control is also conceivable. Therefore, in the above-mentioned common network, information for time synchronization is exchanged, and each control device synchronizes the time.

As a background art in this technical field, there is Japanese Unexamined Patent Application Publication No. 2009-284054 (Patent Document 1). Patent Document 1 discloses a communication system including a base station that can establish direct time synchronization with UTC transmitted by a time reference device and a base station that cannot establish direct time synchronization, and the communication system cannot establish direct time synchronization. A base station acquires time error information from a base station with which direct time synchronization can be established, selects a master station for establishing time synchronization based on the acquired information, and sends a delay amount measurement signal for delay amount measurement. is transmitted to the master station, the master station transfers the delay amount measurement signal to the base station, measures the delay amount E and notifies it to the base station, and the base station establishes time synchronization with the master station based on the delay amount E A communication system is described.

JP 2009-284054 A

In the communication system described in Patent Literature 1, time synchronization is established by selecting a base station having a smaller number of stages from the original clock master from a plurality of base stations that are clock masters. However, Japanese Patent Laid-Open No. 2004-100000 does not describe a technique for considering the amount of deviation between the clock master and the clock of the own station, or for determining one clock master by arbitrating from information shared among a plurality of base stations.

Therefore, the present invention provides a control device that realizes time synchronization by arbitrating information shared between a plurality of control devices, continues highly accurate real-time control, and realizes highly accurate control that improves product quality and accuracy. for the purpose of providing

A representative example of the invention disclosed in the present application is as follows. That is, a control device that constitutes a control system that executes control over a controlled device, and includes a communication unit that transmits and receives information about the control device, and information received from the control device that is a time master device via the communication unit A shared data storage unit for storing time synchronization information, and a synchronization update unit for controlling storage of time synchronization information in the shared data storage unit of the own control device in synchronization with storage in the shared data storage unit of the other control device. a time management unit for detecting a clock deviation amount with respect to the time master device and storing the detected clock deviation amount in the shared data storage unit; and a clock deviation stored in the shared data storage unit. It is characterized by comprising an arbitration unit that selects the time master device based on the quantity and arbitrates with other control devices to determine the time master device.

According to one aspect of the present invention, highly accurate real-time control can be realized. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is a diagram showing a configuration of a control system according to Example 1; FIG. FIG. 2 is an explanatory diagram illustrating the configuration of a control device according to the first embodiment; FIG. 3 is a diagram showing a functional configuration of a control device according to Embodiment 1; FIG. FIG. 5 is a diagram showing another functional configuration of the control device according to the first embodiment; 4 is a timing chart showing operation timings of the control device according to the first embodiment; 4 is a diagram illustrating an example of contents of an information holding unit of the control device according to the first embodiment; FIG. 4 is an explanatory diagram illustrating an example of contents of a shared data storage unit of the control device according to the first embodiment; FIG. 5 is a diagram showing an example of time synchronization information of the control device according to the first embodiment; FIG. 4 shows an example of corrected time synchronization information of each control device according to the first embodiment. FIG. 10 is a diagram showing a state of time synchronization operation of the control device according to the first embodiment; 7 is a flow chart of processing in which the control device (control system) according to the first embodiment shares acquired information and time synchronization information acquired from sensors. 5 is a flowchart of processing in which the control device according to the first embodiment computes a control command and the control devices share the control command; It is an explanatory view explaining an example which applied the control device concerning Example 2 to the steel system. FIG. 12 is an explanatory diagram illustrating an example in which the controller according to the third embodiment is applied to an FA system;

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that substantially the same or similar configurations are denoted by the same reference numerals, and redundant description may be omitted if the description overlaps.

First, the configuration of the control system according to the first embodiment will be explained.

FIG. 1 is a diagram showing the configuration of a control system according to the first embodiment.

In the control system of the first embodiment, a control device (control A) 100, a control device (control B) 101, and a control device (control C) 102 are connected via a common network 1 to form a distributed control system.

Control devices 100, 101, and 102 output control commands (control data such as control signals and command values) to operating devices (controlled devices to be controlled) such as motors 8 and 11 and actuators 9 installed in the field. and control the operating equipment in real time. In other words, the distributed control system is composed of control devices that execute control over operation devices.

The common network 1 is, for example, a network that performs data communication according to a communication method configured according to the IEEE standard called TSN (Time Sensitive Network), an industrial network that is standardized according to IEC 61784, etc., and is capable of time division control. A network that improves time determinism in communication delays between controllers by using time-slotted communication based on Moreover, as a form of connection, a wired cable connection or a wireless connection such as a mobile phone network or a wireless LAN may be used.

The control device 100 has a CPU (Central Processing Unit) 1001 and a memory 1002 . Similarly, control device 101 has CPU 1011 and memory 1012 , and control device 102 has CPU 1021 and memory 1022 .

The memory 1002 has an area for holding a program A that runs on each control device, an area for holding information A acquired by each control device, and shared data shared between the control devices via the common network 1. is provided (shared data area). The shared data here includes acquired information obtained in control A and information such as control commands received from other control devices. Similarly, the memory 1012 has an area for holding the program B and the held information B, and an area for holding the shared data, and the memory 1022 has an area for holding the program C and the held information C, and An area for holding shared data is provided.

A sensor A 7 , a motor A 8 and an actuator A 9 are also connected to the control device 100 via a field network 20 . Similarly, a sensor B10 and a motor B11 are connected to the control device 101 via a field network 21, and a sensor C12 and a sensor C13 are connected to the control device 102 via a field network 22. FIG.

The field networks 20, 21, and 22 may be networks defined by IEC61158, for example. Alternatively, the control device 100 or the like and the detection device 7 or the like or the operation devices 8 and 9 or the like may be directly connected to input/output digital signals or analog signals. In this case, the control device 100, etc., each detection device 7, etc., and each controlled object 8, 9, etc. are preferably connected by a plurality of input/output signal lines.

The control device 100 shares sensing data input from the sensor 7 with the control device 101 and the control device 102 via the common network 1 as shared data. Similarly, the control device 101 shares sensing data input from the sensor 10 as shared data with the control device 100 and the control device 102 via the common network 1, and the control device 102 receives data from the sensors 12 and 13. , and shares shared data with the control device 101 and the control device 102 via the common network 1 .

In particular, the control device 102 calculates, for example, a control command (command value) to the motor 8, the actuator 9, and the motor 11 from the shared input data, and shares the control command with the control device 101 and the control device 102. do. On the other hand, the control device 100 controls the motor 8 and the actuator 9 by the shared control commands, and similarly the control device 101 controls the motor 11 by the shared control commands.

The sensors 7, 10, 12, and 13 installed in the field are detection devices, and detect and acquire acquired information, which is state quantities such as various flow rates, temperatures, pressures, tensions, and rotation speeds. do.

Next, the configuration of the control device 100 according to the first embodiment will be explained.

FIG. 2 is an explanatory diagram illustrating the configuration of the control device 100 according to the first embodiment.

The control device 100 has a CPU 1001 , a memory 1002 , a communication control section 1003 , an interface section 1004 , a nonvolatile storage medium 1005 , a bus 1006 and an input/output section 1007 .

Although the control device 100 will be described here, the control devices 101 and 102 also have the same basic configuration as the control device 100 .

A CPU 1001 is a central processing unit that controls the operation of each component of the control device 100 .

The memory 1002 is a temporary storage area used when the CPU 1001 operates, and stores an operating system (hereinafter referred to as an OS) transferred from the nonvolatile storage medium 1005, application programs, and the like. .

In addition, the memory 1002 has an area for holding a program A that operates on each control device, and an area for holding held information A acquired by each control device (information acquired by each control device from a detection device or a controlled object). , an area is provided for holding shared data (obtained information and control commands obtained by control A) shared among the respective control devices via the common network 1 .

The communication control unit 1003 performs data communication with the control device 101 and the control device 102 via the common network 1 . As a data communication method, for example, the functions of the MAC (Media Access Control) layer of the IEEE802.3 standard may be implemented. Examples of implementation of the communication control unit 1003 include ICs (Integrated Circuits), FPGAs (Field Programmable Gate Arrays), and gate arrays. Also, the communication control unit 1003 may be integrated with the CPU 1001 .

Furthermore, the communication control unit 1003 has a function of executing a time synchronization protocol by exchanging time synchronization packets using a network. In other words, the communication control unit 1003 has a function of measuring time when transmitting and receiving a time synchronization packet, and a function of setting and adding a correction value to the time synchronization packet. IEEE1588, IEEE802.1AS, NTP, and SNTP are used as such time synchronization protocols. The communication control unit 1003 also has a time management function based on synchronous time, and communicates synchronous time information to the control devices 101 and 102 .

Interface unit 1004 transmits and receives data to and from common network 1 . The interface unit 1004 implements, for example, IEEE802.3 physical layer functions. Note that the interface unit 1004 may be included in the communication control unit 1003 .

Although the control device 100 has one communication control unit 1003 and one interface unit 1004 in FIG. 2, it may have multiple communication control units 1003 and multiple interface units 1004 .

The nonvolatile storage medium 1005 is an information storage medium, and stores, for example, the OS, applications, device drivers, programs that operate the CPU 1001, and execution results of the programs.

The nonvolatile storage medium 1005 is composed of, for example, a hard disk drive, solid state drive, flash memory, or the like. In addition, the nonvolatile storage medium 1005 may be composed of an easily removable USB memory, solid state drive, or the like as an external storage medium.

The input/output unit 1007 is an input/output interface that acquires information from a device connected to the control device 100 , such as the sensor 7 , and controls the motor 8 and the actuator 9 . The input/output unit 1007 is implemented with, for example, the functions of the various field networks 20 described above, digital input/output functions, and analog input/output functions. Although one signal line from the input/output unit 1007 is illustrated in FIG. 2, there may be a plurality of signal lines.

A bus 1006 connects the CPU 1001, memory 1002, communication control unit 1003, nonvolatile storage medium 1005, and input/output unit 1007 so as to be able to communicate with each other.

Next, the functional configuration of the control device according to the first embodiment will be explained.

3 is a diagram illustrating a functional configuration of a control device according to the first embodiment; FIG.

The control device shown in FIG. 3 has a time synchronization unit 300, a communication unit 301, a synchronization update unit 302, a shared data storage unit 303, a time management unit 304, an input/output control unit 305, an information holding unit 306, and an arbitration unit 307. That is, it is preferable that the control device 100, the control device 101, and the control device 102 have these functional units. Particularly preferably, the control device 100 and the control device 101 have these functional units.

The time synchronization unit 300 executes a time synchronization procedure. The time synchronization protocol executed by the time synchronization unit 300 is IEEE1588, IEEE802.1AS, NTP, SNTP, and the like described above. Note that the time synchronization unit 300 synchronizes the time with the control device 101 and the control device 102 using the time measured at the time of transmission or reception of the time synchronization packet by the communication unit 301 described later. In other words, the time synchronization unit 300 synchronizes time with other control devices that make up the distributed control system.

Note that the time synchronization unit 300 may be implemented by an application that operates on the CPU 1001, and the communication control unit 1003 may be implemented by a hardware logic circuit such as an IC or FPGA. Also, the time synchronization unit 300 may be composed of both the software of the CPU 1001 and the hardware of the communication control unit 1003 . In this case, it is preferable that the communication control unit 1003 processes the function of measuring the transmission timing and the reception timing of the time-synchronized packet and the generation of the time-synchronized packet format.

The communication unit 301 is a functional unit that connects to the common network 1 and performs communication based on the communication protocol of the common network 1 . For example, the communication unit 301 is composed of software operating on the CPU 1001 , a communication control unit 1003 and an interface unit 1004 . That is, the communication unit 301 transmits information about its own control device to other control devices and receives information about other control devices from other control devices via the common network 1 . The communication unit 301 transmits information (sensor information) acquired by the self-control device regarding the self-control device, and receives information (sensor information) acquired by the other control device regarding the other control device.

The synchronous update unit 302 holds the communication contents received from the communication unit 301 . The synchronous update unit 302 stores information to be held in the shared data storage unit 303 described later according to the synchronous time information (including time notification and time notification interrupt) notified from the time management unit 304 described later. That is, the synchronous update unit 302 updates shared data (information) from the shared data storage unit 303 of another control device in synchronization with storage of shared data (information) in the shared data storage unit 303 of another control device. In synchronization with the storage, the shared data (information) is stored in the shared data storage unit 303 of the own control device.

The shared data storage unit 303 is a functional unit that holds shared data shared among the control devices. A shared data area for each control device is assigned to the shared data storage unit 303 . For example, each control device performs periodic broadcast communication, and the receiving control device identifies the source control device and updates the corresponding shared data area. The shared data storage unit 303 stores information held in the information holding unit 306, which will be described later. The shared data storage unit 303 stores shared data transmitted from other control devices, and stores control commands for controlled objects calculated by the calculation unit 401, which will be described later.

The time management unit 304 manages synchronous time information in an information holding unit 306 described later in each control device based on the synchronous time.

The input/output control unit 305, for example, acquires acquired information from the sensor 7 connected to the control device 100, controls the motor 8 and the actuator 9, and inputs/outputs information. That is, the input/output control unit 305 acquires acquired information from the detection device and inputs/outputs information for controlling the controlled object.

The information holding unit 306 holds sensor information and the like input from the input/output control unit 305 . The information holding unit 306 is configured by, for example, a ring buffer, and when holding the sensor information, the information holding unit 306 receives synchronous time information notified from the time management unit 304 (sensor information added with the time when the sensor information is acquired). information), that is, the sensor information and the time when the sensor information was acquired. The information holding unit 306 also receives and holds information from the time management unit 304 regarding the state of time synchronization. The information holding unit 306 then stores the held data in the shared data storage unit 303 . Also, the information holding unit 306 acquires and holds information stored in the shared data storage unit 303 .

The arbitration unit 307 selects a clock for time synchronization from among the control devices connected to the common network 1 based on the time synchronization information of each control device connected to the common network 1, which is stored in the shared data. Select master. For example, if it does not receive a message from the clock master, then it has lost communication with the clock master and elects a new clock master. Disconnection of communication may occur, for example, due to instability of wireless communication, or disconnection of a wired communication line due to disconnection of a cable or disconnection of a connector.

As described above, the control device according to the first embodiment includes the time synchronization unit 300 that synchronizes time with other control devices that configure the distributed control system, and the other control device that transmits information about the own control device to the other control device. It has a communication unit 301 that receives information about the control device, an information holding unit 306 that adds synchronization time information to the information and holds the information, and a shared data storage unit 303 that stores shared data.

Also, the synchronization update unit 302 transmits shared data via the communication unit 301 .

Next, another functional configuration of the control device according to the first embodiment will be described.

FIG. 4 is a diagram illustrating another functional configuration of the control device according to the first embodiment;

The control device shown in FIG. 4 includes a time synchronization unit 300, a communication unit 301, a synchronization update unit 302, a shared data storage unit 303, a time management unit 304, an input/output control unit 305 (not shown), an information holding unit 306, and an arbitration unit 307. and a computing unit 401 . Note that the time synchronization unit 300, the communication unit 301, the synchronization update unit 302, the shared data storage unit 303, the time management unit 304, the input/output control unit 305, the information holding unit 306, and the arbitration unit 307 are the functional units shown in FIG. are the same.

This control device particularly has an arithmetic unit 401 and corresponds to the control device 102 . Note that the control device shown in FIG. 3 may have the calculation unit 401 . That is, the control device 102 has an arithmetic unit 401 .

A computing unit 401 computes necessary control commands to control motors and actuators connected to the input/output control unit 305 . Arithmetic processing in the computation unit 401 is executed using acquired information (sensor information) acquired by each control device, which is acquired from the shared data storage unit 303 . The calculation unit 401 reads acquired information (sensor information) stored in the shared data storage unit 303 and calculates a control command. The calculated control command is stored in the shared data storage unit 303 and shared with other control devices (the control device 100 and the control device 101). That is, the computing unit 401 computes a control command for the controlled object based on the shared data transmitted by the communication unit 301 .

The control command assigned to the own control device (the control device 100 and the control device 101) is read from the shared data storage unit 303 of the own control device and sent to the input/output unit 1007 shown in FIG. 2 (the input/output control unit shown in FIG. 305) are output to the motors and actuators connected. Note that the calculation unit 401 is implemented by software that operates on the CPU 1001 .

Next, operation timings of the control device according to the first embodiment will be described.

FIG. 5 is a timing chart showing operation timings of the control device according to the first embodiment, and shows a state in which the control system executes processing based on a predetermined control cycle.

FIG. 5(a) shows that each shared data of the control device 100, the control device 101, and the control device 102 is shared at the beginning of the control cycle.

The control device 100 shares data, the control device 101 shares data when the data sharing time of the control device 100 ends, and the control device 102 shares data when the data sharing time of the control device 101 ends. Then, when the data sharing time of the control device 102 ends, the CPU of each control device executes other processing such as calculation and control until the start time of the next control cycle.

That is, each control device acquires and holds sensor information and time synchronization information until the next data sharing time, so that the shared data storage unit 303 of each control device can be controlled by the synchronization updating unit 302. It is updated every cycle and shares the data.

FIG. 5(b) shows that the control device 102 computes the control command and shares the computation result (control command).

When the data sharing period of the control device 101 ends, the control device 102 calculates a control command based on sensor information, which is shared data transmitted from the control devices 100 and 101, and sensor information in the control device 102. .

Then, at the next data sharing time, the obtained calculation result (control command) is shared (the control device 102 transmits the obtained calculation result (control command) to the control device 100 and the control device 101), and the control device 100 And the control device 101 controls the corresponding motors and actuators according to the control commands sent from the control device 102 .

Next, an example of contents of the information holding unit 306 of the control device according to the first embodiment will be described.

FIG. 6 is a diagram illustrating an example of contents of the information holding unit 306 of the control device according to the first embodiment.

FIG. 6 shows an example of the content of the holding area of the information holding unit 306 of each control device at time t1, and FIG. FIG. 6B shows a holding area 61, which is an example of the content of the holding area of the information holding unit 306 of the control device 101, and FIG. Holding area 62, which is an example of the holding area contents of 306, is shown.

The holding area 60 stores the sensor information a acquired by the sensor 7 connected to the control device 100 and the time synchronization information at together with the acquired time. The holding area 61 stores the sensor information b acquired by the sensor 10 connected to the control device 101 and the time synchronization information bt together with the acquisition time. In the holding area 62, the sensor information c1 and c2 acquired by the sensors 12 and 13 connected to the control device 102 and the time synchronization information ct are stored together with the acquisition times.

The information stored in the holding area 60 of each control device is stored in the shared data storage section 303 of each control device.

The calculation unit 401 of the control device 102 calculates control commands based on data information acquired from other control devices and the own control device stored in the shared data storage unit 303 of the control device 102 . That is, the sensor information of the sensor 7 acquired by the control device 100, the sensor information of the sensor 10 acquired by the control device 101, and the sensor information of the sensors 12 and 13 acquired by the control device 102 are used for this calculation. be done.

Next, an example of contents of the shared data storage unit 303 of the control device according to the first embodiment will be described.

FIG. 7 is an explanatory diagram illustrating an example of contents of the shared data storage unit 303 of the control device according to the first embodiment.

In the control device 102, before calculating the control command, sensor information (sensor value a) and time synchronization information (time synchronization at) acquired by the sensor 7 in the control device 100, and sensor information acquired by the sensor 10 in the control device 101 Information (sensor value b) and time synchronization information (time synchronization bt), sensor information (sensor values c1 and c2) acquired by the sensor 12 and the sensor 13 in the control device 102 and time synchronization information (time synchronization ct) are It is stored in the shared data storage unit 303 as the shared data 70 .

Then, the control device 102 calculates a control command based on the sensor information, and stores the calculation result (control command value) in the shared data storage section 303 .

Next, an example of time synchronization information of the control device according to the first embodiment will be explained.

FIG. 8 is a diagram showing an example of the time synchronization information of the control device according to the first embodiment, which is the time synchronization information extracted from the shared data 70 of FIG.

FIG. 8A shows time synchronization information 80 when the control device 102 is the clock master, and stores, for example, the amount of clock deviation from the clock master. The time synchronization at stores a time change difference Δa1 and a time difference Δa2 between the clock of the control device 100 and the control device 102 . Similarly, the time synchronization bt stores the time change difference Δb1 between the clock of the control device 101 and the time change between the control device 102 and the time difference Δb2. Since the control device 102 is the clock master to which the control device 102 provides the reference time, each value of the time synchronization ct is zero. These values are also held in the holding area 60 of each controller. The CPU 1001 (arithmetic unit 401) adds the time change difference and the time difference to correct the clock.

Here, when the control device 102, which is the clock master, leaves the shared network and selects the next clock master, the above-described arbitration unit 307 refers to the shared time synchronization information and connects to the common network 1. A control device with a small time difference in the amount of clock deviation from the control device 102 is selected from among the control devices that have been set. After the control device 101 is selected and becomes the clock master, the time synchronization information 81 becomes as shown in FIG. 8(b). That is, the time synchronization at stores the difference Δa1′ in time change between the clock of the control device 100 and the control device 101, and the difference Δa2′ in time. Since the control device 101 is the clock master that provides the reference time, each value of the time synchronization bt is zero.

The arbitration unit 307 may determine the control device that becomes the clock master based on the communication channel information stored in the shared data storage unit 303 . For example, quality information of the common network 1 to which each control device is connected may be used. Further, when the common network 1 has a wireless connection form, the control device to be the clock master may be determined by evaluating the connection stability based on the radio wave intensity, information on whether it is a base station or a relay station, and the like. .

In addition, it is not necessary to share the shared time synchronization information for all control devices connected to the network. You may By limiting the number of pieces of time synchronization information stored, the capacity of the shared memory can be reduced.

FIG. 9 shows an example of corrected time synchronization information of each control device when the control device 101 is selected as the clock master of the control system according to the first embodiment.

FIG. 9A shows corrected time synchronization information 90 of the control device 100, to which the time synchronization information when the clock master is the control device 102 is added. By the control device 100 performing the time synchronization operation based on this time synchronization information, it is possible to maintain the state of time synchronization when the control device 102 was selected as the clock master, and to realize highly accurate real-time control.

FIG. 9B shows corrected time synchronization information 91 of the control device 101, to which the time synchronization information when the clock master is the control device 102 is added. By the control device 101 performing the time synchronization operation based on this time synchronization information, it is possible to maintain the state of time synchronization when the control device 102 was selected as the clock master, and similarly high-precision real-time control. can be realized.

This time synchronization information 90 is calculated from the values held in the shared memory stored in the holding area 60 and may be additionally written in the holding area 60 .

FIG. 10 is a diagram showing the state of the time synchronization operation of the control device 100 according to the first embodiment, and shows the state where the clock master is changed from the control device 102 to the control device 101 at time tm.

Line 111 is the time on the clock of control device 102 and line 112 is the time on the clock of control device 100 . The time synchronization protocol described above detects the difference in the clock from the clock master, and is controlled to adjust the clock of the control device 100 for synchronization with the time 111 . At this time, as described above, the difference in time change of the clock and the difference in time are shared by each control device. Line 113 is the time on the clock of control device 101 . With the corrected time synchronization information, even after time tm, the state of time synchronization when the control device 102 is selected as the clock master can be maintained, and highly accurate real-time control can be realized.

As another method, when the control device 101 distributes the time information, the same effect can be obtained by distributing the time information to which the amount of clock deviation from the control device 102 is added.

Further, when the connection of the control device 102 to the common network 600 is restored, by selecting the control device 102 as the clock master, time synchronization can be continued without deviation.

Furthermore, the control device that has been disconnected from the common network 600 continues to correct the clock using the corrected time synchronization information held in the holding area 60 until the connection is restored again, and accesses the common network 600. When the connection is restored, time synchronization can be continued without deviation. Further, even when arbitration with the clock master takes time, self-running based on the corrected time synchronization information enables time synchronization to be continued without deviation even when the connection with the clock master is restored.

Next, a process of sharing shared information by the control device (control system) according to the first embodiment will be described.

FIG. 11 is a flowchart of processing for sharing shared data (acquired information and time synchronization information) acquired from sensors by the control device (control system) according to the first embodiment.

At step S91, the operation flow of the control system starts.

At step S92, the control system is activated.

In step S93, the time synchronization unit 300 performs time synchronization operation with other control devices. Also, as described above, a clock master is selected.

In step S94, each control device stores the acquired sensor information and time synchronization information in the information holding unit 306 together with the acquired time.

In step S95, each control device stores the sensor information and time synchronization information stored in the information holding unit 306 in the shared data storage unit 303, and shares them as shared data with other control devices.

These steps are repeatedly executed in each control cycle.

Next, a process in which the control device (control system) according to the first embodiment calculates a control command and the control device (control system) shares the control command will be described.

FIG. 12 is a flowchart of processing in which the control device (control system) according to the first embodiment calculates a control command and the control device (control system) shares the control command.

At step S101, the operation flow of the control system starts.

At step S102, the control system is activated.

In step S103, the time synchronization unit 300 performs time synchronization operation with other control devices. Also, as described above, a clock master is selected.

In step S104, each control device shares shared data. This step corresponds to step S95.

At step S104, the calculation unit 401 calculates a control command.

At step S105, each control device shares the calculated control command.

These steps are then repeated for each control cycle.

The method of sharing the time synchronization information 80 between the control devices may be a method of storing it in the user defined area of the time synchronization packet in the time synchronization protocol.

As described above, according to the first embodiment, it is possible to provide a control device that maintains time synchronization without deviation, improves product quality, and realizes highly accurate control.

Next, an embodiment in which the control device described above is applied to a steel system will be described.

FIG. 13 is an explanatory diagram illustrating an example of applying the control device according to the second embodiment to a steel system.

In the steel system, a steel hot rolling facility 800 is controlled by control devices 100 , 101 , 102 , 104 and 105 . Control device 100 , control device 101 , control device 102 , control device 104 and control device 105 are controlled by terminal 500 connected to common network 600 . Further, the control device 100, the control device 101, the control device 102, the control device 104 and the control device 105, and the terminal 500 connected to the common network 600 are time-synchronized with the control device 105 as a clock master, for example.

The steel heated in the heating furnace 801 is put into the hot rolling equipment 800 . The hot rolling facility 800 has a rough rolling mill 802 , a finishing rolling mill 803 , a cooling facility 804 and a winder 805 .

The temperature of heating furnace 801 acquired by temperature sensor 700 is input to control device 100 via field network 601 .

The control device 101 controls the feed control/strip speed sensor unit 701, adjusts the rotation speed of the roughing mill 802, and detects the steel feed speed.

The control device 102 controls the rolling control/strip thickness sensor unit 702, adjusts the rotation speed and tension of the finishing rolling mill 803, and detects the thickness of the steel.

The temperature of cooling equipment 804 obtained by temperature sensor 703 is input to control device 104 .

The control device 105 controls the winding control/plate thickness sensor/plate speed sensor unit 704, adjusts the rotation speed of the winder 805, and detects the steel plate thickness and the steel winding speed. In addition, the control device 105 executes calculation of control commands for each control device.

Further, each control device executes control according to the operation flow described above.

Here, even if the control device 105 is disconnected from the other control device due to disconnection of the wired cable connected between the control device 105 and the common network 600, the other control device that continues the connection can maintain stable time synchronization. Therefore, the optimum control command can be calculated from the obtained information, and high-quality and high-precision control can be realized.

Next, an embodiment in which the control device described above is applied to an FA (Factory Automation) control system will be described.

FIG. 14 is an explanatory diagram illustrating an example of applying the control device according to the third embodiment to an FA system.

A server 520 , a monitoring terminal 521 , a wireless bridge 522 and a wireless bridge 523 are connected to the LAN 620 . Also, the control devices 120 and 121 are wirelessly connected to a wireless bridge 522 , and the control devices 122 and 123 are wirelessly connected to a wireless bridge 523 . Thereby, control of the control devices 120, 121, 122, and 123 is executed. Further, the control devices 121, 122, and 123 are time-synchronized with the control device 120 as a clock master.

Control device 120 controls connected PLC (Programmable Logic Controller) 720 , and control device 121 controls connected PLC 721 . Also, the controller 122 controls the PLC 722 and the controller 123 controls the PLC 723 .

PLC 720 controls picking robot 822 , PLC 721 controls conveyor motor 823 and camera 821 , PLC 722 controls painting robot 824 , and PLC 723 controls camera 825 .

The products (manufacturing objects) mounted on the belt conveyor 826 are placed in a predetermined position/orientation (for example, the correct orientation of the product) by the picking robot 822 controlled by the PLC 720 . Belt conveyor 826 is moved at a predetermined speed by conveyor motor 823 controlled by PLC 721 . A product moving on the belt conveyor 826 is photographed by a camera 821 controlled by the PLC 721, and this camera 821 observes whether this product is installed at a predetermined position.

The PLC 721 acquires the image of the product photographed by the camera 821 and inspects whether the product is installed at a predetermined position. A painting robot 824 controlled by the PLC 722 paints the surface of the product. A camera 825 controlled by the PLC 723 photographs the painted product and observes whether the product is painted correctly. The PLC 723 acquires images of the product captured by the camera 825 and performs inspections to see if the product has been painted correctly.

Camera information (sensor information) from the camera 821 is input to the control device 121 , and camera information (sensor information) from the camera 852 is input to the control device 123 .

Based on the input camera information, the control device 121 and the control device 122 select shared data, which is camera information for the same product. Compute control commands. Also, the control device 122 calculates a control command for the painting robot 824 based on the shared data.

A picking robot 822 installs the product, a camera 821 photographs the product, and a painting robot 824 paints the product. The time at which the camera 825 photographs the product is managed by the time management unit 304 of the control device.

Here, when the wireless connection between the control device 120 and the wireless bridge 522 is disconnected, as described in the first embodiment, from the time synchronization information of the shared memory, the control devices 121, 122, and 123 maintaining the connection A new clock master is arbitrated and selected from among them.

As described above, according to the third embodiment, it is possible to stably maintain time synchronization even when the wireless connection is disconnected. Therefore, the optimum control command can be calculated from the obtained information, and high-quality and high-precision control can be realized.

The control device of Embodiment 1 can be applied to various control systems such as FA systems, steel systems, water and sewage treatment systems, power generation control systems, elevator control systems, railway control systems, automobile control systems, and construction machine control systems. can be used.

As described above, the control device of the present embodiment stores the time synchronization information received from the control device, which is the time master device, via the communication unit 301 that transmits and receives information about the control device, and the communication unit 301. a shared data storage unit 303; a synchronization updating unit 302 that controls storage of time synchronization information in the shared data storage unit 303 of the own control device in synchronization with storage in the shared data storage unit 303 of another control device; A time management unit 304 that detects the amount of clock deviation with respect to the master device and stores the detected amount of clock deviation in the shared data storage unit 303; Since it is equipped with an arbitration unit 307 that selects a master device and arbitrates with other control devices to determine a time master device, time synchronization is realized by arbitrating from information shared among a plurality of control devices, and high-precision real-time It is possible to provide a control device that can continue control, improve product quality, and realize highly accurate control.

In addition, when the communication with the time master device is cut off, the arbitration unit 307 newly selects the time master device from the other control devices. can continue.

In addition, since the arbitration unit 307 selects the control device with the smallest deviation of the clock stored in the shared data storage unit 303 as the time master device, the amount of time correction becomes small, and the time error can be reduced.

In addition, the time management unit 304 stores information on the connected communication path in the shared data storage unit 303, and the arbitration unit 307 selects the time master device based on the stored information on the communication path. Stable time synchronization can be realized by using time synchronization information transferred through a stable communication channel.

In addition, when the communication with the control device, which is the original time master device, is restored, the arbitration unit 307 selects the control device as the time master device. As unnecessary, stable time synchronization can be realized.

In addition, after the communication of the self-control device is interrupted, the time management unit 304 corrects the clock by adding the deviation amount of the clock of the self-control device until the connection is reconnected, so that the time synchronization becomes impossible. However, the system as a whole can continue to operate.

In addition, the shared data storage unit 303 has a storage area for storing time synchronization information received from a predetermined number of control devices, and stores time synchronization information of control devices with a small clock difference. By limiting the number, the storage capacity of the shared data storage unit 303 can be reduced.

The amount of clock deviation is the difference in time and the difference in time change. Since the clock is corrected by adding the time change difference, the time can be synchronized more accurately than the time synchronization using the time difference. That is, if the difference in time change is not used, the time difference between the control devices becomes large after the time synchronization. However, the time error can be reduced for a long period of time by synchronizing the time using the difference in time change.

It should be noted that the present invention is not limited to the embodiments described above, but includes various modifications and equivalent configurations within the scope of the appended claims. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to those having all the described configurations. Also, part of the configuration of one embodiment may be replaced with the configuration of another embodiment. Moreover, the configuration of another embodiment may be added to the configuration of one embodiment. Further, additions, deletions, and replacements of other configurations may be made to a part of the configuration of each embodiment.

In addition, each configuration, function, processing unit, processing means, etc. described above may be realized by hardware, for example, by designing a part or all of them with an integrated circuit, and the processor realizes each function. It may be realized by software by interpreting and executing a program to execute.

Information such as programs, tables, and files that implement each function can be stored in storage devices such as memories, hard disks, SSDs (Solid State Drives), or recording media such as IC cards, SD cards, and DVDs.

In addition, the control lines and information lines indicate those considered necessary for explanation, and do not necessarily indicate all the control lines and information lines necessary for mounting. In practice, it can be considered that almost all configurations are interconnected.

1, 600... Common network 20, 21, 22, 601... Field network 1001, 1011, 1021... CPU, 1002, 1012, 1022... Memory, 7, 10, 12, 13... Sensor, 8, 11... Motor, 9 Actuators 100, 101, 102, 104, 105, 120, 121, 122, 123 Control device 1003 Communication control unit 1004 Interface unit 1005 Non-volatile storage medium 1006 Bus 1007 Input Output unit 300 Time synchronization unit 301 Communication unit 302 Synchronization update unit 303 Shared data storage unit 304 Time management unit 305 Input/output control unit 306 Information holding unit 307 Arbitration unit , 401... Arithmetic unit 520... Server 521... Monitoring terminal 700, 703... Temperature sensor 701... Feed control/strip speed sensor 702... Rolling control/strip thickness sensor 704... Winding control/strip thickness sensor Plate speed sensor 720, 721, 722, 723 PLC 822 Picking robot 821 Camera 823 Conveyor motor 824 Painting robot 825 Camera 826 Belt conveyor 800 Rolling facility 801 Heating Furnace 802 Rough rolling mill 803 Finishing rolling mill 804 Cooling facility 805 Winding machine.

Claims (11)

A control device that constitutes a control system that controls a controlled device,
a communication unit that transmits and receives information about the control device;
A shared data storage unit that stores time synchronization information received from a control device that is a time master device via the communication unit;
a synchronization updating unit that controls storage of time synchronization information in the shared data storage unit of the own control device in synchronization with storage in the shared data storage unit of the other control device;
a time management unit that detects a clock deviation amount with respect to the time master device and stores the detected clock deviation amount in the shared data storage unit;
A control device, comprising: an arbitration unit that selects a time master device based on the amount of deviation of the clock stored in the shared data storage unit, and arbitrates with other control devices to determine the time master device. The control device according to claim 1,
The control device, wherein the arbitration unit newly selects the time master device from the other control devices when communication with the time master device is interrupted. The control device according to claim 1,
The control device, wherein the arbitration unit selects, as the time master device, the control device with the smallest deviation amount of the clock stored in the shared data storage unit. The control device according to claim 1,
The time management unit stores information on the connected communication path in the shared data storage unit,
The control device, wherein the arbitration unit selects the time master device based on the stored information of the communication path. The control device according to claim 1,
When the control device is determined to be the time master device, the time management unit adds a clock shift amount of the control device and transmits time synchronization information to the other control devices. . The control device according to claim 2,
The control device, wherein the arbitration unit selects the control device as the time master device when communication with the control device, which is the original time master device, is restored. A control device according to claim 6,
The control device, wherein the time management unit corrects the clock by adding a deviation amount of the clock of the self-control device until reconnection after the communication of the self-control device is interrupted, and runs by itself. The control device according to claim 1,
The control device, wherein the shared data storage unit has a storage area for storing time synchronization information received from a predetermined number of the control devices, and stores the time synchronization information of the control device with a small clock difference. The control device according to claim 1,
The clock shift amount is a time difference and a time change difference,
The arbitration unit selects a control device having a minimum time difference between the clocks as a time master device,
The control device according to claim 1, wherein the control device corrects a clock by adding the time difference and the time change difference. A control system that controls a controlled device,
comprising a plurality of control devices and a network communicatively connecting the plurality of control devices;
each of the plurality of control devices,
a communication unit that transmits and receives information about the control device;
A shared data storage unit that stores time synchronization information received from a control device that is a time master device via the communication unit;
a synchronization updating unit that controls storage of time synchronization information in the shared data storage unit of the own control device in synchronization with storage in the shared data storage unit of the other control device;
a time management unit that detects a time change difference and a time difference of the clock with respect to the time master device, and stores the detected clock difference in the shared data storage unit;
a control system comprising: an arbitration unit that selects a time master device from the time difference between the clocks of the control devices stored in the shared data storage unit, and arbitrates with other control devices to determine the time master device. . A time synchronization method executed by a control device that constitutes a control system that controls a controlled device,
The control system has a plurality of control devices and a network communicably connecting the plurality of control devices,
The time synchronization method includes:
The control device stores time synchronization information received from a control device that is a time master device in a shared data storage unit,
The control device controls storage of time synchronization information in the shared data storage unit of its own control device in synchronization with storage in the shared data storage unit of the other control device,
The control device detects a time change difference and a time difference of the clock with respect to the time master device, and stores the detected clock time difference in the shared data storage unit,
A time synchronization method, wherein the control device selects a time master device from the difference in the clocks of the control devices stored in the shared data storage unit, and arbitrates with other control devices to determine the time master device.

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